Well, they dont have to pay royalties for using their own core and the external interface to the rest of the system utilizes AMBA, for which they have an implementation for other things already. So - the only cost to them is maintaining the ARC core. Now they can modify the core to their hearts content and thus gain benefit within the sub-system.

thank you Brain for the explanation...what is the reason for Synopsys pushing it since ARM pretty much dominanted that space? I would imagine Synopsys has to be desigining their IP to work with ARM...double effort?

ARC or Argonaut RISC Core was another English processor IP company that had reconfigurable processor core much like Tensillica's. They were acquired by Virage Logic which was then acquired by Synopsys in 2010.